#!/bin/bash
# lkm : a silly kernel module dev - build, load, unload - helper wrapper script
# License: MIT
# Kaiwan NB

# Turn on unofficial Bash 'strict mode'! V useful
# "Convert many kinds of hidden, intermittent, or subtle bugs into immediate, glaringly obvious errors"
# ref: http://redsymbol.net/articles/unofficial-bash-strict-mode/
set -euo pipefail

unset ARCH
unset CROSS_COMPILE
name=$(basename "${0}")

#-------------- r u n c m d -------------------------------------------
# Display and run the provided command.
# Parameter(s): the command to run
runcmd()
{
local SEP="------------------------------"
[[ $# -eq 0 ]] && return
echo "${SEP}
$*
${SEP}"
eval "$@"
[[ $? -ne 0 ]] && echo " ^--[FAILED]"
}

### "main" here

[[ $# -ne 1 ]] && {
	echo "Usage: ${name} name-of-kernel-module-file (without the .c)"
	exit 1
}
[[ "${1}" = *"."* ]] && {
	echo "Usage: ${name} name-of-kernel-module-file ONLY (do NOT put any extension)."
	exit 1
}

echo "Version info:"
which lsb_release >/dev/null 2>&1 && {
  echo -n "Distro: "
  lsb_release -a 2>/dev/null |grep "Description" |awk -F':' '{print $2}'
}
echo -n "Kernel: " ; uname -r

runcmd "sudo rmmod $1 2> /dev/null" || true
#runcmd "make clean"
runcmd "sudo dmesg -C" || true
runcmd "make || exit 1" || true

[[ ! -f "$1".ko ]] && {
  echo "[!] ${name}: \"$1.ko\" has not been built, aborting...
(Note though, that this can happen when the module's named differently)."
  exit 1
}

runcmd "sudo insmod ./$1.ko && lsmod|grep $1" || true
# Ubuntu 20.10 onward has enabled CONFIG_SECURITY_DMESG_RESTRICT ! That's good for security
# So we need to 'sudo' dmesg; thanks to @gregbuchholz for pointing this out
runcmd "sudo dmesg" || true
exit 0